The proposed investigation has as its long time goal, the complete structure determination of the psychopharmacologically important amine oxidases of which there are two types, namely the diamine and the monoamine oxidase. Simultaneously the proposed investigation has as its long time goal, the determination of the mechanism of action of these enzymes. During the proposed grant period, the following studies are proposed. 1. The isolation of crystals suitable for crystal X-ray diffraction studies. 2. The structural characterization of the cofactors present in the enzymes. 3. Attempted transformation studies of the monoamine oxidase to a diamine oxidase and vice-versa by the use of oxidizing and reducing agent. 4. Complete amino acid sequence of the monoamine oxidase. Laser Raman and X-ray absorption spectroscopic studies of the bovine plasma amine oxidase. 5. Continuation of mechanistic studies of the bovine monoamine oxidase. 6. The determination of the dimensions of the active sites of the enzyme as well as distances between the cofactors or essential amino acid residues present in the enzyme. These studies should provide valuable structure-function information data and may possibly lead to the biochemical basis of mental disease. Since there are many biogenic amines in the brain and nervous system such as epinephrine, norepinephrine, tyramine, dopamine, serotonin, etc. which can be inactivated by one or the other of these amine oxidases, the findings will be of great interest to neurochemists, neuropharmacologists, physiologists, biochemists, etc.